Ferritic stainless steel sheet exhibiting small increase in strength after aging heat treatment, and method of producing the same

Abstract

A ferritic stainless steel sheet exhibiting small increase in strength after aging heat treatment in the present invention contains, by mass %, C: 0.020% or less, Cr: 10.0% to 25.0%, N: 0.020% or less, Sn: 0.010% to 0.50%, and one or more of Ti: 0.60% or less, Nb: 0.60% or less, V: 0.60% or less, and Zr: 0.60% or less so as to satisfy the following Equation (1), in which the difference between stress σ1 (N / mm2) after prestrain imparting tensile deformation with 7.5% of strain, and upper yield stress σ2 (N / mm2) when the steel sheet is subjected to heat treatment at 200° C. for 30 minutes and then to tension again after the tensile deformation is 8 or less.(Ti / 48+V / 51+Zr / 91+Nb / 93) / (C / 12+N / 14)≧1.0  (1)

Description

TECHNICAL FIELD[0001]The present invention relates to a ferritic stainless steel sheet exhibiting small increase in strength after aging heat treatment, and a method of producing the same. Particularly, the present invention relates to a ferritic stainless steel sheet capable of suppressing strengthening by performing aging heat treatment on a steel sheet such as ferritic stainless steel generally containing a large amount of Cr, and a method of producing the same.[0002]Priority is claimed on Japanese Patent Application No. 2013-52423, filed Mar. 14, 2013, the content of which is incorporated herein by reference.BACKGROUND ART[0003]Since ferritic stainless steel has excellent corrosion resistance, it is used for various applications such as a kitchen or the like. In the case of stainless steel, the states of C and N present in the steel and corrosion resistance are closely connected. That is, when C and N are present in a solid solution state in the steel, Cr carbonitrides are forme...

AI Technical Summary

Benefits of technology

The present invention provides a way to make a ferritic stainless steel sheet that has very little strength improvement after being treated with aging heat. This is done by controlling the components of the steel and the production method, which helps to reduce the strain that occurs when the steel is held at high temperatures for long periods of time.

Problems solved by technology

The solid-soluted C (N) remaining in grains is fixed to dislocation introduced by applying strain and then becomes an obstacle to dislocation movement.

), a wrinkle-like shape (stretcher strain) is formed due to the occurrence of a yield point, which causes a problem in some cases.

The stretcher strain causes a problem in that product properties are remarkably deteriorated.

In addition, since the stretcher strain spoils the outer appearance, polishing is required to remove the stretcher strain.

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